When provided with RNA precursors, ejaculated mammalian spermatozoa synthesize RNA. The role this RNA plays in gamete maturation and fertilization is unknown. To help define the physiological function of transcription in spermatozoa, I propose to purify and characterize the RNA, ascertain its relationship to RNA synthesized in spermatids and in mitochondria and define what proteins are encoded by RNA from spermatozoa.